The protagonist Luke is a thin boy living in the Sun Tribe that celebrates strength. In order to get the recognition from his fellow tribe members, Luke tries to integrate into it. By chance, Luke begins to study methods of flying. One day, during the sudden raiding by the Moon Tribe, Luke takes a hot air balloon to fly up in the sky when the Sun Tribe is losing. This scares the Moon Tribe away and Luke, having relieved the tribe from its plight, finally gains the approval from everyone.